The present invention relates to a camera with a changeable focal length, and more particularly to a changeable focal length camera equipped with a safety control device which acts when a taking lens system is interrupted in operation.
Recent compact cameras are equipped with taking lens systems of the type in which the focal length can be changed between various focal lengths, for example between a relatively short focal length suitable for wide-angle photography and a relatively long focal length suitable for telephotography. Such changeable focal length cameras have taking lens systems which generally include an axially movable lens and an extra lens which is displaced from or moved into the optical path of the taking lens system upon changing the focal length. In many instances, a position sensor is provided in association with the axially movable lens of the lens system in order to detect that the axially movable lens has moved to one of two possible lens positions, or to a position between the possible lens positions.
Other changeable focal length cameras have lens barrels which are thrust back and forth or protruded from and retracted into a camera body. Therefore, the lens barrel is sometimes interrupted from smooth movement due to external obstructions such as fingers, foreign articles or the like. In order to eliminate such interruptions, conventional changeable focal length cameras are provided with safety mechanisms which hold the axially movable lens when the movement of the lens barrel is interrupted. If a shutter release is operated when the axially movable lens is held at a position out of one of the possible lens positions, the camera cannot be properly focused on a subject. Therefore, the conventional changeable focal length cameras have the disadvantage that pictures are absolutely out of focus when the movement of the lens barrel is interrupted, and a timely shutter release is lost.